Cole, Daniel and Bryan had some erasers in the ratio of 2 : 3 : 5. Bryan gave 40% of his erasers to Cole and Daniel. As a result, Cole had the same number of erasers as Daniel and Bryan had 31 fewer erasers than Cole.

1. What was the percentage increase in Cole's erasers after receiving from Bryan?
2. How many erasers did Daniel have at first?

Cole	Daniel	Bryan	Total
2 u	3 u	5 u	10 u
+ 2 u		- 2 u
3.5 u	3.5 u	3 u	10 u

(a)
Number of erasers that Bryan gave away
= 40% x 5
= ⁴⁰₁₀₀ x 5
= 2 u

Number of erasers that Cole and Daniel each had in the end
= (10 u - 3 u) ÷ 2
= 7 u ÷ 2
= 3.5 u

Increase in the number of erasers that Cole had
= 3.5 u - 2 u
= 1.5 u

Percentage increase in Cole's erasers after receiving from Bryan
= ^1.5₂ x 100%
= 75%

(b)
3.5 u = 3 u + 31
3.5 u - 3 u = 31
0.5 u = 31

1 u = 31 ÷ 0.5 = 62

Number of erasers that Daniel had at first
= 3 u
= 3 x 62
= 186

Answer(s): (a) 75%; (b) 186